Transcriptomic characterization of platelet-rich fibrin-induced macrophage responses identifies U937 cells as a sensitive bioassay

Platelet-rich fibrin (PRF) is extensively utilized to enhance localized tissue healing, a process that critically depends on the transient polarization of macrophages toward a pro-inflammatory phenotype. Given that PRF, like other blood clot derivatives, may intrinsically modulate macrophage behavior, we conducted a comprehensive screening assay to characterize the global macrophage response to PRF exposure. To this end, we employed two widely used monocytic cell lines-U937 (histiocytic lymphoma) and THP-1 (acute monocytic leukemia)-as in vitro models to investigate macrophage responses. Cells were exposed to lysates derived from PRF, and transcriptomic alterations were profiled using bulk RNA sequencing. Differential gene expression analysis was performed, with significance determined by an adjusted p-value threshold of <0.05. In U937-derived macrophages, gene expression profiling revealed a transcriptional signature consistent with inflammatory activation. Clustering of upregulated genes highlighted pathways associated with chemokine activity (e.g., CCL2, CCL3, CCL4, CCL5, CCL7, CCL8, CCL20, CCL23, CCL26, CXCL5, CXCL6, CXCL8, CXCL16, and PPBP), RAGE receptor binding (FPR1, S100A8, S100A9, and S100A12), IgG binding (FCGR1A, FCGR2A, FCGR2B, and FCGR3A), prostaglandin biosynthesis (CBR1, CD74, EDN1, FABP5, IL1B, MIF, PTGES, and PTGS1), and collagen catabolism (CTSL, FAP, MMP3, MMP7, MMP9, MMP12, MMP14, MMP19, and MRC2). In contrast, PRF exposure in THP-1 cells primarily enriched genes involved in steroid biosynthesis, suggesting a more limited or distinct response. These findings underscore U937 cells as a more responsive and appropriate bioassay for modeling inflammatory macrophage polarization in response to PRF. Moreover, the identified gene signatures recapitulate key aspects of early wound healing, providing a relevant platform for studying macrophage reactivation in chronic wound environments.